<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <style>
        /* 父容器使用 Flex 布局 */
       .flex-container {
            display: flex;
        }

        /* 子元素平均分配宽度 */
       .column {
            flex: 1;
            padding: 20px;
            background-color: lightblue;
            margin: 5px;
        }
        .column2 {
            flex: 1;
            padding: 20px;
            background-color: lightblue;
            margin: 5px;
        }
        .column3 {
            flex: 2;
            padding: 20px;
            background-color: lightblue;
            margin: 5px;
        }
    </style>
</head>

<body>
    <div class="flex-container">
        <div class="column">这是第一栏的内容。</div>
        <div class="column2">这是第二栏的内容。</div>
        <div class="column3">这是第三栏的内容。</div>
    </div>
</body>

</html>